At present, IP network of telecommunication service provider can only provide data services as possible. Along with the number of broadband network subscribers increases, the service requirements on IP network are getting more and more. The real-time services, such as voice and videoconference etc., have strict requirements for QoS.
As shown in FIG. 1, a whole IP network of a telecommunication service provider comprises access/edge layers and a core layer. Subscribers of the IP network can access to the edge router E through various access means, such as XDSL, HFC, Ethernet, lease line or WLL etc. The edge router E is responsible for management of the subscribers and is connected to the core router RH that is responsible for forwarding and routing IP packets. An IP network can be huge, for example, a national wide network of a telecommunication service provider may comprise thousands upon thousands of core routers and edge routers. In view of the convenience of management and stability of network route, the IP network can be divided into a plurality of independent route management areas as shown with dot lines in FIG. 1. The whole network consists of a plurality of network areas and the connections between them.
A network can be divided into areas based on administration region, such as city, province and nation; or based on other ways. Usually, an IP network of a telecommunication service provider is divided based on administration region and each area may be an IP Autonomous System (AS).
Due to design ideas, in general there is no means for guaranteed QoS in prior IP network. In order to adapt the development of network applications, various methods for IP QoS have been proposed, including Integrated Service (Int-Serv) model and Differentiated Service (Diff-Serv) model. Among them, the Diff-Serv model can be used to provide QoS support together with Multiprotocol Label Switching (MPLS) technology. At present, a combination of the Int-Serv model and Diff-Serv model is a common method in which the Int-Serv model is used in the access network and the boundary and the Diff-Serv model is used in the backbone network. The MPLS technology can be used when the Diff-Serv model is used in the backbone network.
When the Diff-Serv model is used, if only priority is set in Type of Service (ToS) in order to guarantee QoS, the effect is unpredictable although it has the advantage of high line utilization factor. Therefore, further improvement for Diff-Serv has been implementing. Some organizations and vendors introduce an independent bearer control layer on the backbone Diff-Serv and establish a set of special Diff-Serv QoS signaling mechanism. In order to promote application of the Diff-Serv, IETF, some vendors and institutes together push the Internet 2 on the Qbone experiment network, which takes Bandwidth Broker (BB) to manage network resources and topology. Also, some other vendors propose methods of managing resources and topology and coordinating QoS capability of each Diff-Serv area using similar QoS server/resource manager technology. In all these methods, a bearer control layer for managing network resources and topology is specially established for Diff-Serv basic network. As shown in FIG. 2, this Diff-Serv mode with professional network resource management is called a DiffServ model with an independent bearer control layer.
In the Diff-Serv model with an independent bearer control layer, an edge router of the network makes classification and mark of DS field for each group, and uses the DS field of an IP packet or EXP information of a MPLS packet to carry priority information of the IP group. In the core node of the network, the router selects corresponding forwarding processing for the packet based on the priority information. Servers in the bearer control layer, including BB or QoS server/resource manager, configure management rules and network topology and allocate resources for service bandwidth requests of subscribers. The specified bandwidth can be shared through the coordination with subscribers via Service Level Agreement (SLA). The bearer network control servers of each management area transfer service bandwidth requests and results, path information allocated for the service requests by the bearer network resource manager etc. between each other through signaling. At present, the problems such as it is difficult to implement, plan, operate and maintain are existed in the prior Diff-Serv model with independent bearer control layer, such as a bandwidth broker model of the Qbone.
In the first prior technical scheme, as shown in FIG. 3 illustrating an Internet2 BB model, Internet2 defines corresponding BBs for each Diff-Serv management area, and the BB is responsible for handling bandwidth application requests from subscriber computers, service servers S or network servicing staff. The BB determines whether or not to allow the bandwidth application according to the preserved resource condition of the current network, configuration policies and the SLA of the service signed with the subscriber.
As shown in FIG. 4, a bandwidth manager records a large amount of static and dynamic information including various kinds of SLA configuration information, topology information of the physical network, configuration information and policy information of routers, user authentication information, information about the current preserved resources and information about occupation condition of network etc. At the same time, the bandwidth manager also records route information in order to determine a traffic stream route and the position of a downstream bandwidth manager in crossing areas.
In the bandwidth manager model of Internet2, since the bandwidth manager directly manages the resource information and configuration information of all routers in the area, there is a problem that topology and management is very complicated. At the same time, since the bandwidth manager needs to record the dynamic route information of the area, there is a problem that the route table is updated frequently which will result in the unstableness of the network preservation. In addition, it is difficult for the service route determined by the dynamic route information in the area accord with the real forwarding route of the traffic stream.
Since there are too many problems in the bandwidth manager model, the model has not been put into business application till now.
In the second prior technical scheme which is a Rich QoS solution proposed by NEC of Japan, as shown in FIG. 5, the QoS Server (QS) is regarded as a key element. The policy server (CS), directory server (DS) and network management monitoring server are also included in the solution. The policy server implements parameter setting and configuration for related routers according to the policy configuration information such as the information about QoS server and management interface. The directory server is a concentrated database for storing network device configuration information, user information and QoS information. The network management monitoring server is responsible for collecting information such as block state of routers and links etc., which can be reference to the QoS server for selecting route for service application.
The QoS server is responsible for allocating a bearer route that satisfies the QoS requirement based on the network topology and resource condition of the bearer network. It is necessary to preset the topology and bandwidth condition in QoS server and pre-configure the rules for route selection. When the service server sends a bandwidth request to the QoS server, the QoS server records the resource request of this call, and allocates a bearer route that satisfies the requirements according to QoS requirements, the current topology and resource condition of the bearer network for this service request, and returns the allocation result to the service server.
The QoS server sends a corresponding LSP policy modification command to the policy server according to the bandwidth occupation condition of the service. Then, the policy server configures a correspondent edge router according to the commands from the QoS server.
The edge router will use MPLS LSP display route technology to recreate or adjust LSP according to the path determined by the QoS server.
In the Rich QoS scheme proposed by NEC, it is also a complicated bearer network that the QoS server manages, and there are a large amount of routers. The QoS server and policy server use MPLS LSP display route technology to inform edge routers. The mode of establishing end-to-end LSP has the disadvantage of poor expansibility and limited network scale. So, the scheme is unable to satisfy the end-to-end service requirements in a national wide public network.
Since the bandwidth manager directly manages the resource information and configuration information of all routers in the area, there is a problem that topology and management is very complicated. In the solutions proposed by other vendors such as NEC, the QoS server still manages a complicated bearer network. The mode of establishing end-to-end LSP with display route technology used in bearer network has the disadvantage of poor expansibility and limited network scale and it cannot satisfy the end-to-end service requirements in a national wide public network. Consequentially, how to provide guaranteed QoS from the original edge router to the destination edge router for the service request of subscribers, such as VoIP or video-telephone etc., in a large IP backbone network of the telecommunication service provider is a problem needs to be solved urgently.